Dry plate process printing



DRY PLATE PROCESS PRINTING Filed NOV. 19, 1927 @liga 10 INVENTOR.

ATTORNEYS.

Patented Nov. 8, 193.2l

UNITED STATES PATENT OFFIE CLARENCE L. JOHNSTON, OF NIAGARA FALLS, NEW YORK, ASSIGNOIB, T0 .AMmICAN SALES BOOK COMPANY, LIMITED, OF TORONTO, ONTARIO, CANADA, A CORPORATION OF ONTARIO, CANADA BEY PLATE PROCESS PRINTING Application led November 19, 192'?. Serial No. 234,381.

This invention relates to improvements in process printing, and with reference to some of its more particular features, it relates to improvements in dry plate process printing of the type utilizing mercurized plates, and

being adapted for use in various printing applications such, for example, as photolithographic or photomechanical printing. i

It is a general object of the invention to improve and perfect the art of dry plate process printing in such a manner as to decrease the time and expense incident to production of the printing plates, and at the same time to produce aplate which is especially durable in keeping qualities, andfhighly wear-resistant in use so as to have a long life under severe conditions of wear. p

Still another object of the invention is to provide a mercuric printing plate or blank which will have a high degree of permanency both before and after it is prepared for print- 1n further object is to provide an improved dry plate for process printing of the type utilizing mercury and having its layers of different metals arranged in a novel and advantageous manner so as to take advantage of the affinity of the metals to provide a plate having great durability, superior wearing and keeping qualities, and being capable of producing printing of high quality.

Another object of the invention is to provide an -improved inexpensive, rapid and otherwise commercially practicable method for making mercurio printing plates.

Other objects of the invention will be in part pointed out in connection with the following detailed description of certain illustrative but preferred embodiment of the invention and will be in part obvious in connection therewith. v

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the article possessing the features, properties, and the relation of elements, which-are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a more complete understanding of the nature and objects of the invention, reference is had to the following detailed description of certain illustrative but preferred embodi- ,l

ments of the invention and to the accompanying drawing, in which Fig. l is a diagrammatic sectional perspective view of a fragment of a completed printing plate embodying the invention;

Fig. 2 is a view similar to Fig. l showing a blank compound plate which is utilized in forming the completed plate;

Fig. 3 is a view similar to Fig. 1 showing an initial step in the process of forming the completed plate;

Fig. 4: is a view similar to Fig. 3 showing a later step in the process;

Fig. 5 is a view similar to Fig. -1 of a modified form of a-completed plate, and

Fig. 6 is a view of a compound plate or baik used in forming the completed plate o 1g. 5.

It will be understood that the several figures of the drawing are largely diagrammatic, and that the thicknesses of the base plate l0 and of the metallic coatings, or platings, and of other applications to the base plates are considerably magnified, in order to disclose the structure more clearly. As a matter of practical construction, the complete printing plate may be thin and 'flexible so as to be readily adapted for application to the cylinders of printing machines, or it may be used upon flat bed machines, in which case it may be thicker and less flexible. The overlying metallic plates or coatings may be quite thin, conforming to known practice in mercurio plates in this respect. The printing plate of this invention may conform in-thickness and dimensions to standard practice as known in the various branches of process printing, and it is well adapted for letter press, for pictorial work, or for combined letter press and pictorial `work, and is adapted also for use in lithographie machines, either direct or offset.

The sections of the drawing figures are taken through the design, so that the construction ma be more readily observed.

ccording to the illustrative embodiments herein disclosed, the improved plate comprises primarily a base plate having a surface composed of ink-attractive printing areas forming the design to be printed and bemg of hard durable metal, to which the ink readily adheres, and non-printing, ink repellent areas formed by metallic mercury adhering to the surface of an amalgamable metal. The invention is herein illustrated particularly in what may be referred to by analogy as a relief plate, since the non-printing areas are made by removing parts of a thin metallic surface coating on the plate, leaving other parts of the surface coating intact so as to form the raised printing design. The amount of relief therefore will be dependent upon the thickness of the overlying metallic coating. The ability of the plate to hold ink on the relief surface of the design while excluding it from the other surfaces, is not however due primarily to the relief effect mentioned, but rather to the difference in physical characteristics of these surface parts.

Referring to the drawing for a detailed description of the embodiments there shown, and first to the improved plate as shown in Fig. l, a plate 10 forms the base upon which the completed printing surface is built up. The base plate 10 may be of any one of various metals or alloys having preferably, a characteristic that it does not form an amalgam with mercury. Iron, steel, or copper is found L:uitable for this purpose. One surface of this base plate is then coated, 0r plated, in any known manner, such as an electrical plating process, with a material which amalgamates with mercury, but whose compound with mercury does not readily disintegrate either with time or under use, so that when amalgamated it will continuously be in condition to present a surface of free mercury whenever mercury is brought into Contact therewith, thus forming an ink repellent surface. The material used to form the amalgamable coating is preferably such that the mercury is not absorbed thereby to such. an extent as to disintegrate the same, or to form undermining or undercutting of the edges of the adjacent printing area of the design.

The most suitable materials for this purpose at present known are silver and tin, silver being utilized in the modification of Figs. 1, 2 and 3 to form the plating or coating 11. l/Vhile the noble metal silver as mentioned has advantages and is preferred yet the other amalgamable noble met-als, gold, platinum, palladium or rhodium may be used. In this instance, that is, where a silver coating is employed, it is desirable to plate the surface of the base l0 with a coating l2 of a bonding metal before applying the silver coating. Copper is found to be suitable for this purpose as it forms a good binder for holding the silver coating in place and preventing flaking, or bulging thereof away from the supporting surface. If desii ed, the

base plate itself may be made of copper throu hout, since its `function is to provide a mec ianical support for the layer of silver and it is not attacked by an amalgam of inercury and silver. Superposed upon the layer 11 is a plating or coating 13 (Fig. 2) made of a material suiiiciently hard to withstand the Wear of printing and of a character to adhere firmly to the surface of the underlying silver coating, does not form an amalgam with mercury, forms a surface to which the printing ink readily adheres, and has an affinity for the silver to which it tends to adhere firmly so as to hold the overlying coating in position. This outer coating 13 is also of such a nature as to be readily removed by a mordant which will not attack the underlying silver coating. For the overlying coating 13 nickel has been found to be particularly satisfactory, while cobalt or iron also gives good results.

The plates or coatings 11, 12, and 23 may be placed in position upon the base plate 10 in any preferred known manner as by electrolytic processes, and thus constructed the plate forms what may be termed a blank or printing plate, as shown in Fig. 2, which may subsequently be treated to form the finished printing plate. This biank with the layers assembled as described, will keep almost indefinitely Without deterioration and stores of such plates may be kept on hand for preparation at any time desired. It will be understood that the term print-ing plate7 and similar expressions are to be herein construed as not necessarily limited to the plate in its fully completed condition, but to comprehend also the incomplete conditions as herein described. i

In the preparation of the complete printing plate from the blank of Fig. 2 the design to be printed may be applied to the surface in accordance with any one of several known methods such, for example, as employed in half-tone work, photo-engraving, photo-lithographing, etc. The process of applying the design to the blank plate is usually a photographic process and may, for example, include coating the surface with bichromated gelatine or fish glue, thus providing a sensitized surface. When thus prepared the design may be applied to the surface in accordance with the known processes i by exposure to a negative or transparency. The plate is then washed and burnt in in the usual manner, leaving the insoluble light exposed areas or patches upon the surface so as to form the design.

In order to illustrates the method of applying the design, these insoluble patches are shown in Fig. 3 in the form of hollow rectangles 14, thus depicting the design diagrammatically, the parts of the surface of the nickel plate surface not occupied by the design being therefore exposed. These patches of the desi are in acid resist which is not attacke by the mordant dur7 ing the etching process. The soluble, or uncxposed portions of the sensitized coating are removed by washing in the usual manner, thus leaving the ground surface of the plate,

that is, the surface unoccupied by the design,

free from the acid resist.

When in the form just described and as shown in Fig. 3, the plate is subjected to an acid bath which eats away the exposed parts of the nickel coating 13, while the parts occupied by the design remain intact. This condition of the late is shown in F ig. 4, the exposed parts o the nickel plate being entirely removed, so as to expose the surface of the underlying silver coat 11, while the nickel coating remains intact at parts thereof protected by the acid resist, thus forming the ink carrying parts of the design which, it will be observed, are slightly in relief with the adjacent surfaces of the silver coating 11. As above mentioned, the ability to hold ink by the ink carrying surfaces and to vexclude it from the other surfaces is due primarily to the selective character of the plate surface brought about by the use of mercury. The

selective power of the mercurial surface thus arranged is so great that extreme fineness of detail can be reproduced without blurring.

When the etching is completed the acid resist design 14 may be removed in any preferred known manner such, for example, as by the use of coal oil or gasoline, thus exposing the ink carrying surfaces of the design 15, the plate then substantially assuming the form as indicated in Fig. 1. The surface of the plate is now treated with mercury, which forms an amalgam with the surface of the silver coating 11, but does not combine with or adhere to the nickel forming the ink carrying surfaces 15 of the design. The

amalgam surface is formed right up sharply to the edges of the design surfaces 15 so that there is a sharp line of demarkation therebetween. All parts of this mercury or amalgam surface are ink repellent and the print.- ing ink will not adhere thereto, while the nickel design surfaces 15 readily'take the ink which adheres thereto as the ink rolls are passed over the surface.

The mordant used in etching is chosen so as to have little or no effect upon the silver or other amalgamable surface while readily attacking and cutting away the non-amalgamable coating as the nickel coating described. For example, it has been found that about of sulphuric acid mixed with about 10% of nitric acid will dissolve nickel rapidly, but acts very slowly upon silver; hydrochloric acid will dissolve cobalt, but does not affect silver; sulphuric acid will also dissolve cobalt, but its action upon tin is negligible; dilute hydrochloric and sulphuric acid will dissolve iron, but has little effect on tin or silver. A preferred etching fluidV for nickel and silver coatings as described is formed by combining about 90% .of ferric chloride with about 10% of nitric acld. Therefore, by building up a plate in layers, as above described, a printing plate is provided that is'practical for mercurio process.

- It will be observed that the layer of silver extends uninterruptedly over the areas of the printing plate which ultimately form the ,i printing and non-printing areas. ln other words, the layer of amalgamable metal, when the plate is completed and ready` for use, extends under or underlaps the areas forming the design; it also extends continuously between the design areas and the adjacent nonprinting areas. lt will, therefore, be seen that the silver layer underlaps, that is lies under the design areas in lapping relation therewith, extending continuously between the design areas and adjacent areas.

According to the modification ofthe invention, as illustrated in Figs. 5 and 6, the base plate 10 may be similar to that as above described. Upon the surface of the base plate is a thin coating of tin 16 which may be ap plied in any, preferred known manner, while over the coating 16 a thin coating 17 of nickel is applied entirely covering the surface of the rst coating. ln this case, as before, the different metallic layers which come into contact with each other are chosen so as to have an affinity for each other whereby they are firmly bonded together so as to prevent flaking or peeling off even after the mercury has been applied to the amalgamable layer. As tin bonds or adheres readily to the iron base plate 10, no further bonding means is ordinarily required in order to secure satisfactory adherence. l'n a like manner the coating of nickel bonds firmly with the underlying tin coating.

The base or supporting plate 10 with the superimposed metallic laye-rs thereon provides a blank plate which may be constructed in advance and later prepared for printing at such a. time-as desired. The process ofI preparing the blank plate of Fig. 6 to form the completed printing plate, as shown in Fig. 5, may be similar to the processes above described. It will be understood that the design inacid resist isapplied to the nickel surface of the blank of Fig. 6 in a manner similar to that above described, and that the etching is similarly accomplished to form the co-mpleted plate having a printing surface as shown in llig. 5.

Plates prepared as above described are remarkable in their keeping qualities, .even after engraving, or when set aside for some time such plates may be immediately placed in active use by the application of mercury to the surface. With the combinations of metal herein outlined, there is no tendency of the mercury to undermine the printing izo areas. Moreover, should occasion be found to discontinue. the printing operation temporarily, leaving the plates in the press, no special treatment is required either for their temporary reservation or to restore their condition w en it is desired to resume operations. It is only necessary to insure that there shall be suiicient mercury present at all times.

The metals forming the layers as herein described, and the arrangement of said layers, are at present deemed most suitable in carrying out the invention, but it will be understood that other metals having similar properties may be employed.

Since certain changes may be made in carrying out the above process, and certain modifications in the article which embodies the invention may be made without departing from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A process for preparing a printing surface which includes, applying a design in acid resist to a non-amalgamable metallic surface with an underlying layer of silver and subsequently treating with a mordant which actively attacks the non-amalgamable surface while having little effect upon the silver layer, so as to remove the non-amal amable surface and to expose the amalgama le material except at parts of the surface occupied by the acid resist. l

2. A process for preparing a printing sulfface which includes applying upon a base a thin coating of silver, superposing upon the silver coating a thin coating of nickel, applying upon the nickel coating a design in acid resist, and then treating with a mordant composed of approximately 10% of nitric acid mixed with approximately 90% of ferrie chloride.

3. A printing plate having a thin layer of silver and an overlying thin layer of nickel.

4. A printing plate having a base of ferrous material with a thin layer of silver bonded to the surface thereof by an intervening metallic layer and a coating of non-amalgamable metal overlying the silver layer forming the design in relief with the adjacent exv posed surface of said silver layer, said silver layer underlapping the said design.

5. A printing plate having, on a ferrous base, successive overlapping layers of copper, silver, and a non-amalgamable metal.

6. A printing plate having a base of ferrous material with a thin layer upon the surface thereof of a metal selected from a group including silver and tin, and a coating of nonamalgamable metal overlying said thin layer and forming they design in relief with the ex osed parts thereof. y

A printing plate having a base including a continuous layer of copper, a continuous layer of silver continuously covering said base and a continuous layer of nickel superposed upon and continuously covering said silver layer.

8. A printing plate having a base, a continuous layer of silver continuously covering said base and a continuous layer of nickel superposed upon and continuously covering said silver layer.

9. A process for preparing a printing surface which includes applying to a ferrous base plate a thin layer of an amalgamable metal with an intervening layer of a bond increasing metal, said amalgamable metal being selected from a group including a noble metal and tin, `superposing upon the layer of amalgamable metal a layer of non-amalgamable metal, applying to the surface of the layer of non-amalgamable metal a design in acid resist and then subsequently treating with a mordant which attacks and acts to remove the parts of the non-amalgamable layer unprotected by said design while having little or no effect upon the underlying layer of amalgamable metal, which is thus exposed through the removed parts of the overlying layer to form the design.

10. A dry process printing plate having a base, a layer of amalgamable noble metal superposed upon said base, and a layer of non-amalgamable metal superposed upon the amalgamable layer of noble metal, the said layers of metal continuously overlapping each other at design and non-design areas of the blank. /1

11.,A dry process printing plate having a thin layer of an amalgamable noble metal, and an overlying thin layer of a non-amalgamable meta-l, said layer of noble metal underlapping the non-amalgamable layer and extending continuously between the design and non-design areas of the latter.

12. A dry process printing plate having a base, a layer of an amalgamable noble metal superposed upon said base, and a layer of a non-amalgamable ink-adhesive metal superposed upon said irst mentioned layer and providing the ink carrying surface, said layer of noble metal underlapping the ink-carrying layer and extending continuously between the design and non-design areas.

13. A dry process printing plate having a thin layer of an amalgamable metal selected from a group including a noble metal and tin, and an overlying thin layer of a nonamalgamable ink-adhesive metal adapted to form the ink-carrying design.

14. A printing plate having a thin layer of silver, and an overlying thin layer of a non-amalgamable metal adapted to form the ink-carrying design, said second mentioned layer being relatively non-resistant to the action of a mordant to which the silver layer is relatively resistant.

15. A printing plate including a thin layer of an amalgamable noble metal, and an overlying design of non-amalgamable metal in relief with the surface of the layer of noble metal.

16. A dry process printing plate including an underlying layer of metal, an overlying design of a non-amalgamable metal in relief with and attached to the underlying layer, said underlying metallic layer being of noble metal and underlapping the design and being amalgamable With mercury to form an unaltering amalgam Which avoids impairment to the attachment of the design to the underlying layer.

17. A printing plate having a base including a layer of copper, a silver layer superposed upon the copper layer, and a design of a non-amalgamable metal superpos'ed in relief upon the silver layer. s

18. A dry process printing plate includmg a non-amalgamable metallic base, a thin coating thereon of a noble metal capable of forming anunaltering amalgam with mercury, a printing coating of a non-amalgamable metal superposed upon and contacting with said first mentioned coating and adapted to form the design in relief, the respective contacting metals of said base and layers having an alnity for each other so as to (promote firm and permanent adherence, an the physical characteristics of said first and second mentioned contacting coatings preventing undercutting by mercurio action.

19. A multiply relief printing plate including an intermediate ply of silver and a supporting ply of base metal to which the silver ply adheres, one of the plies of the printing plate being apertured to expose the silver ply and to form the design in relief, the exposed surface of the silver being amalgamated with mercury.

20. A dry process printing plate including a thin layer of silver on a supporting base and a relief design in nickel superposed upon said silver layer, said` silver layer underlapping said nickel design and extending beyond the bounds of the latter.

In testimony whereof I aiix my signature.

CLARENCE L. JOHNSTON. 

